WO2007025462A1 - A slow-release fertilizer coated with degradable polymer - Google Patents

Abstract

This invention discloses a slow-release fertilizer coated with degradable polymer. The release controlled fertilizer is composed of fertilizer core 1 and outer coated layer, wherein the coated layer comprises (a) a high-barrier organic layer 2, (b) a sulfur contained degradable polymer mixture layer 3 and/or degradable polymer layer 4. The high-barrier organic layer is preferably the inner layer or middle layer. The degradable polymer is selected from one or more of amino resin, acetal resin of polyvinyl alcohol and its copolymer, unsaturated oil resin and natural polymer as well as its derivative. The high-barrier organic layer is preferably nonpolar low molecular weight organic layer or nonpolar polymer layer. The average thickness of the whole layers is 20-200μm and the average thickness of the high-barrier organic layer is 2-25μm. The fertilizer has long release time and brings less or no pollution to environment.

Description

 Degradable polymer coated slow release fertilizer

 Technical field

 The invention relates to a coated slow release fertilizer, in particular to a degradable polymer coated slow release fertilizer, belonging to the field of fertilizer industry.

 Background technique

 At present, slow release fertilizer is the development direction of the world agricultural fertilizer. In particular, the development of coated slow-release fertilizers that develop a coating of degradable materials meets the requirements of environmental protection and social sustainable development, and will become the mainstream of slow-release fertilizers in the future.

 However, the degradable material is a polar material, and the permeation rate of water and fertilizer is very high. Therefore, the release period of the degradable coated slow release fertilizer prepared by using the degradable material is very short, such as simple use. The urea-formaldehyde coated envelope type slow release fertilizer is generally only a few days. Therefore, the degradable coated slow-release fertilizer has a long release period, which is the key to the real application of the degradable coated slow release fertilizer, and is also plagued by the degradable coated slow release fertilizer. The problem solved.

 Chinese patent "coated film slow release urea and its preparation method" (application No. 03132085.6), discloses the use of urea-formaldehyde resin to wrap sheet urea, and tung oil or tung oil modified phenolic resin for the presence of tiny pores or defects on the surface of coated urea Such as cracking and soaking and sealing, in order to manufacture a fully fertilizer-type slow-release urea. However, since the tung oil or tung oil modified phenolic resin which is a degradable polymer has low barrier to water and fertilizer, the soaking and sealing of the urea-formaldehyde resin wrapped with flaky urea does not make the coating to water and fertilizer. The barrier permeability is increased too much, so even though the volume of flake urea is several tens of times that of ordinary industrial urea (for example, its volume is about 22 times the volume of 3.0 mm spherical industrial urea, the specific surface area is 3.0 mm spherical industry The total thickness of the coating is about 120~170/m, but the release period is only a few dozen days. Moreover, the tung oil or tung oil modified phenolic resin dip coating layer is on the outermost surface of the urea coating, and the dip coating layer is easily broken and broken during the storage, transportation, fertilization process, especially mechanical fertilization process of the coated slow release urea. Cracks or defects, at the same time, their toughness is not high (small elongation at break), and the layer has a low bearing capacity. After the coated slow-release urea is fertilized into the field, the thin layer of the dip coating will be broken due to the water absorption of the fertilizer core. , resulting in a shorter release period in actual use.

 Summary of the invention

 SUMMARY OF THE INVENTION It is an object of the present invention to provide a degradable polymer coated slow release fertilizer which has a longer release period and which is completely or almost completely degradable.

 The technical solution for achieving the object of the present invention is: a degradable polymer coated slow release fertilizer consisting of a fertilizer core and a coating on the outer side of the fertilizer core, the envelope comprising: (a) a high barrier organic film layer, (b) a layer of a sulfur-containing degradable polymer mixture and/or a layer of a degradable polymer film.

 In the coating of the degradable polymer-coated slow-release fertilizer of the present invention, the high-barrier organic film layer is preferably the inner layer or the intermediate layer of the entire coating film.

The high barrier organic film layer in the degradable polymer coated slow release fertilizer coating of the present invention is preferably non-polar. The film layer, the material of the non-polar organic film layer may be a non-polar low molecular weight organic substance and an I or a non-polar polymer. In the degradable polymer coated slow release fertilizer of the present invention, the non-polar low molecular weight organic substance may be a wax having a melting point of 40 ° C, a polyolefin having a melting point or a softening point of 40 Å and a molecular weight of ≤2000, and a softening point of 40 Å. One or more of petroleum resins and the like. The non-polar polymer may be polyolefin, polystyrene, butadiene rubber, natural rubber, polyisoprene rubber, styrene butadiene rubber, butyl rubber, ethylene propylene rubber and ethylene propylene diene rubber, styrene One or more of a diene-styrene block copolymer and a styrene-isoprene-styrene block copolymer.

 The degradable polymer used in the degradable polymer coated slow release fertilizer of the present invention is a water-insoluble degradable polymer, and may be an acetal resin of an amino resin, a polyvinyl alcohol and a copolymer thereof, or an unsaturated oleoresin. And one or more of natural polymers and derivatives thereof. Among them, the natural polymer and its derivative may be one or more selected from the group consisting of nitrocellulose, shellac, cellulose acetate, crosslinked starch, chitin derivatives, and lignin derivatives.

 In the film of the sulfur-containing degradable polymer mixture of the degradable polymer coated slow-release fertilizer of the present invention, the average mass fraction of sulfur may be 0% to 95%, preferably 20% to 95%, preferably 50%. ~90%.

 For the degradable polymer coated slow release fertilizer of the present invention, if the high barrier organic film layer is a high barrier polymer film layer or a high barrier polymer film layer is present in the high barrier polymer film layer When the high barrier polymer film layer has an elongation at break, it is preferably greater than the equilibrium expansion ratio of the entire coating film when the degradable polymer coated slow release fertilizer is immersed in water.

 The high barrier organic film layer of the degradable polymer coated slow release fertilizer of the present invention may contain a sustained release modifier. The sustained release modifier may be one of a plasticizer, a water-soluble compound, a vegetable powder, a long-chain fatty acid and an ester thereof, a long-chain fatty alcohol, a rosin and an ester thereof, an asphalt, a clay, a talc powder, a molecular sieve powder, and a bone powder. Or more than one.

 The total average thickness of the coating of the degradable polymer coated slow-release fertilizer of the invention may be 20-200/m, wherein the total average thickness of the high-barrier organic film layer may be 2-25 m, the degradable polymer film The total average thickness of both the layer and the sulfur-containing degradable polymer mixture film layer may be 20 to 190 m; the total average thickness of the degradable polymer film layer may be 0 to 190 / / m, the sulfur-containing degradable polymer mixture film The total average thickness of the layers can range from 0 to 190 m.

The degradable polymer coated slow release fertilizer of the invention is compounded with a high-barrier organic film layer by using a degradable polymer and/or a sulfur-containing degradable polymer mixture film layer, and a high barrier organic film layer for water and The high barrier property of the fertilizer enables the degradable coated slow release fertilizer of the present invention using a degradable polymer as a coating material to have a long release period. Among them, urea-formaldehyde resin and melamine-formaldehyde resin are relatively cheap and degradable polymers, which are much lower than ordinary refractory polymers (such as the cost index of pure fertilizers in 100), urea-formaldehyde resin and melamine-formaldehyde The cost index of the resin is about 450 and 600, respectively, while the cost index of polyurethane and epoxy resin is about 2500 and 2000 respectively, and they are slow release nitrogen fertilizer, urea formaldehyde resin and melamine-formaldehyde tree. The nitrogen content of the fat is about 30% and 54%, respectively. The nitrogen content of the melamine-formaldehyde resin is higher than the nitrogen content of the urea (about 45%), so the urea-formaldehyde resin or the melamine-formaldehyde resin is used as the coating material. The degradable polymer coated slow release fertilizer of the invention is a fertilizer-loaded slow release fertilizer with high fertilizer content and low cost.

 In particular, when the degradable polymer-coated slow-release fertilizer of the present invention is combined with the high-barrier organic film layer, the sulfur is cheaper than the fertilizer, and the sulfur is also fat. In the case of effectively protecting the high barrier organic film layer, the use of the sulfur-containing degradable polymer mixture film layer can greatly reduce the amount of the degradable polymer, and the cost is greatly reduced. At the same time, the membrane layer of the sulfur-containing degradable polymer mixture is more resistant to water and fertilizer than the purely degradable polymer film layer, especially when the sulfur content is high (for example, 80% to 90%), The release resistance of the fertilizer is strong, so that the release period of the degradable polymer-coated slow-release fertilizer of the present invention having a film layer of the sulfur-containing degradable polymer mixture in the envelope can be longer.

 At the same time, by adding a slow release modifier to the barrier organic film layer, the degradable polymer coated slow release fertilizer of the invention can be obtained in a release period with a high barrier organic film layer and The release period value in the range between the release periods of the barrier-free organic film layer, the release period is flexible, effective and economical.

 In addition, the degradable polymer coated slow release fertilizer of the invention adopts a degradable polymer as a main coating material, has no pollution to the environment or little pollution, and is therefore an environmentally friendly environmentally-friendly slow release fertilizer. In particular, when the high-barrier organic film layer is made of a non-polar low-molecular-weight organic substance such as a wax, a polyolefin having a molecular weight of ≤2000 or a polystyrene, and a petroleum resin, a non-polar low-molecular-weight organic substance is generally available in the environment. Biodegradable, the degradable polymer coated slow release fertilizer of the present invention can be a completely environmentally friendly slow release fertilizer. Even if the high barrier organic film layer uses a high barrier polymer, although they are difficult to degrade, they are used in a small amount, and the slow release fertilizer which is completely coated with a refractory polymer as a coating material in the prior art. In contrast, its environmental pollution is small and has obvious advantages.

 DRAWINGS

 1 is a spherical fertilizer core 1 of a degradable polymer coated slow release fertilizer of the present invention, a sulfur-containing degradable polymer mixture film layer 3 - a high barrier organic film layer 2 - a sulfur-containing degradable polymer mixture film layer 3 structure diagram.

 Figure 2 is a structural view of a spherical fertilizer core 1 - a high barrier organic film layer 2 - a sulfur-containing degradable polymer mixture film layer 3 of the degradable polymer coated slow release fertilizer of the present invention.

 Figure 3 is a structural view of a spherical fertilizer core 1 - a sulfur-containing degradable polymer mixture film layer 3 - a high barrier organic film layer 2 of the degradable polymer-coated slow-release fertilizer of the present invention.

 Figure 4 is a structural view of a spherical fertilizer core 1 - a degradable polymer film layer 4 - a high barrier organic film layer 2 - a degradable polymer film layer 4 of the degradable polymer coated slow release fertilizer of the present invention.

 Figure 5 is a structural view of a spherical fertilizer core 1 - a high barrier organic film layer 2 - a degradable polymer film layer 4 of the degradable polymer coated slow release fertilizer of the present invention.

Figure 6 is a spherical fertilizer core 1 of a degradable polymer coated slow release fertilizer of the present invention, a degradable polymer film layer 4 a high-barrier organic film layer 2 structure diagram.

 Figure Ί is a spherical fertilizer core of the degradable polymer coated slow release fertilizer of the present invention 1 a sulfur-containing degradable polymer mixture film layer 3 - a high barrier organic film layer 2 - a structure of a degradable polymer film layer 4 .

 Figure 8 is a structural view of a spherical fertilizer core 1 of a degradable polymer coated slow release fertilizer of the present invention, a degradable polymer film layer 4, a high barrier organic film layer 2, a sulfur-containing degradable polymer mixture film layer 3 .

 Figure 9 is a spherical fertilizer core 1 of a degradable polymer coated slow release fertilizer of the present invention, a sulfur-containing degradable polymer mixture film layer 3 - a barrier organic film layer 2 - a sulfur-containing degradable polymer mixture film layer 3—Structural diagram of the degradable polymer film layer 4.

 Figure 10 is a spherical fertilizer core 1 of a degradable polymer coated slow release fertilizer of the present invention, a degradable polymer film layer 4, a high barrier organic film layer 2, a sulfur-containing degradable polymer mixture film layer 3 - Destruction polymer film layer 4 structure diagram.

 Figure 11 is a structural view of a spherical fertilizer core 1 of a degradable polymer coated slow release fertilizer of the present invention, a high barrier organic film layer 2 - a sulfur-containing degradable polymer mixture film layer 3 - a degradable polymer film layer 4 .

 Figure 12 is a structural view of a spherical fertilizer core 1 of a degradable polymer coated slow release fertilizer of the present invention, a degradable polymer film layer 4, a sulfur-containing degradable polymer mixture film layer 3, a high barrier organic film layer 2 .

 detailed description

 The degradable polymer coated slow release fertilizer of the invention consists of a fertilizer core 1 and an outer envelope of the fertilizer core, and the envelope comprises: (a) a high barrier organic film layer 2, (b) a sulfur-containing degradable polymer The film layer 3 and/or the degradable polymer film layer 4 are mixed.

 In the coating of the degradable polymer-coated slow-release fertilizer of the present invention, the high-barrier organic film layer is preferably the inner layer or the intermediate layer of the entire coating film. In this way, the high barrier organic film layer can be protected by the outer sulfur-containing degradable polymer mixture film layer and the I or degradable polymer film layer, and generally does not break during storage, transportation, and fertilization, even if the machine The process is generally not broken, and the release period is stable and reliable.

 The fertilizer core of the degradable polymer coated slow release fertilizer of the invention may be nitrogen fertilizer, phosphate fertilizer, potassium fertilizer or compound fertilizer. The shape of the fertilizer core may be granular, flake, or the like, but it is preferably granular, and preferably spherical.

 The film of the sulfur-containing degradable polymer mixture in the present invention means a film layer of a mixture of sulfur and a degradable polymer. The envelope of the degradable polymer-coated slow-release fertilizer of the present invention may be a composite film layer of a sulfur-containing degradable polymer mixture film layer and a high-barrier organic film layer, and such a composite film layer is preferred. At this time, the structure of the slow-release fertilizer can be as shown in Fig. 1, Fig. 2 and Fig. 3. The structure of Fig. 1 is superior to that of Fig. 2, and the structures of Figs. 1 and 2 are superior to those of Fig. 3.

The coating film of the degradable polymer coated slow release fertilizer of the invention may also be a composite film layer of the degradable polymer film layer and the high barrier organic film layer. At this time, the structure of the slow release fertilizer can be as shown in FIG. 4, FIG. 5 and FIG. In general, the structure of Fig. 4 is superior to that of Fig. 5, and the structure of Fig. 4 and Fig. 5 is superior to that of Fig. 6. The coating film of the degradable polymer coated slow release fertilizer of the invention may also be a composite film layer of a sulfur-containing degradable polymer mixture film layer, a degradable polymer film layer and a ruthenium barrier organic film layer. Wherein, the structure of the sulfur-containing degradable polymer mixture film layer closely adhering to the high barrier organic film layer is preferred, and the structure of the sulfur-containing degradable polymer mixture film layer closely adhering to the inner surface of the high barrier organic film layer is The film layer of the sulfur degradable polymer mixture is superior to the outer surface of the high barrier organic film layer. At this time, the structure of the slow release fertilizer can be as shown in FIG. 7, FIG. 8, FIG. 9, FIG. 10, FIG. 11, and FIG. Among them, the structures of Fig. 7 and Fig. 9 are preferred among the above six structures, and the structure of Fig. 9 is superior to the structure of Fig. 7. Of course, it can also be a structure of other combinations.

 Further, it is also possible to change the structure based on the structures of Figs. 1 to 12. For example, it may be a multiple composite structure of the envelope structure shown in Figs. 1 to 12, and may be a multiple composite structure in which the envelope structures shown in Figs. 1 to 12 are combined with each other. However, these multiple composite structures are not preferred structures from a process perspective.

 The high barrier organic film layer of the degradable polymer coated slow release fertilizer of the invention means that the transmittance of water and fertilizer is lower than that of the purely degradable polymer film layer, that is, the high barrier organic layer The permeability of the film material to water and fertilizer is lower than that of the degradable polymer used in the envelope to water and fertilizer, and the high-barrier organic film layer and the degradable polymer used in the envelope. The difference between the transmittance of water and fertilizer should be large enough. For example, the permeability of water and fertilizer in high-barrier organic film should be less than that of degradable polymer used in the envelope. One-third of the rate is appropriate, and the bigger the gap, the better. The high barrier organic film layer material may be a high barrier organic low molecular weight organic material such as coumarone-indene resin and mixtures thereof, asphalt and mixtures thereof, or rosin (ester) and mixtures thereof (relative to degradable organic matter) For polymers, it can also be a high-barrier refractory polymer, such as acrylonitrile-butadiene-styrene copolymer (ABS), polyvinyl chloride, nitrile rubber and other low-permeability polymers ( Relative to the degradable polymer). However, the high barrier organic film layer in the degradable polymer coated slow release fertilizer coating of the present invention is preferably a non-polar organic film layer, since the non-polar organic film layer has a low transmittance to water and fertilizer. The water and fertilizer are mainly transmitted through the film defects, so that the thinner non-polar organic film layer can give a long release period of the degradable polymer coated slow release fertilizer of the present invention. The non-polar organic film layer material may be a non-polar low molecular weight organic material or a non-polar polymer, and may have both a non-polar low molecular weight organic material and a non-polar polymer.

Since the non-polar low-molecular-weight organic film layer is prone to cracking, the non-polar low-molecular-weight organic film layer can be combined with the high-barrier polymer film layer to form the high-barrier organic film layer. That is, the high barrier organic film layer of the degradable polymer coated slow release fertilizer of the present invention may also be a composite film layer of a non-polar low molecular weight organic film layer and a high barrier polymer film layer. The non-polar low molecular weight organic film layer is preferably an inner layer in the composite film layer. Among them, the high barrier polymer may be polyurethane, epoxy resin, unsaturated polyester, cyclopentadiene copolymer, phenolic resin, acrylonitrile-butadiene-styrene copolymer (ABS), polyvinyl chloride and A low polarity polymer such as nitrile rubber may also be a non-polar polymer. In addition, the ruthenium barrier organic film layer of the degradable polymer-coated slow-release fertilizer of the present invention may also be a composite film layer of a non-polar polymer film layer and a low-polarity polymer film layer, and low-polarity polymerization. Preferably, the material is a thermosetting, low polarity polymer. This can reduce the amount of non-polar polymer used, because the non-polar polymer coating liquid is generally an organic solution, and the thermosetting low-polarity polymer film layer is combined with the non-polar polymer film layer. Reduce the use of organic solvents. For example, a film of a non-polar polymer such as a butadiene rubber, a styrene-butadiene rubber or a styrene-butadiene-styrene block copolymer and a low-polarity polymer such as a polyurethane, an epoxy resin or an unsaturated polyester. The film layer is composited as a high barrier organic film layer. The non-polar polymer film layer is preferably in the inner layer of the composite film layer.

 In the degradable polymer coated slow release fertilizer of the present invention, when the non-polar low molecular weight organic substance is a separate film layer, the non-polar low molecular weight organic substance may be a wax having a melting point of ≥ 40 ° C, a melting point or a softening point ≥ 40 ° C And one or more of a low molecular weight polyolefin or polystyrene having a molecular weight of ≤2000 and a petroleum resin having a softening point of ≥40 Å. The wax may be petroleum wax, synthetic wax, natural wax, mineral wax or the like; the low molecular weight polyolefin may be polyethylene wax, or other low molecular weight polyolefin such as low molecular weight polypropylene, low molecular weight polyisobutylene. Of course, the molecular weight of the low molecular weight polyolefin or polystyrene can also be ≥ 2000. The melting point or softening point of the non-polar low molecular weight organic substance should be higher than room temperature, preferably 髙, wherein ≥ 60 ° C is preferred, preferably ≥ 85 Ό.

 In the degradable polymer coated slow release fertilizer of the invention, polyolefin, polystyrene, butadiene rubber, natural rubber, polyisoprene rubber, styrene butadiene rubber, butyl rubber and ethylene propylene rubber can also be used. And one or more non-polar polymerizations such as ethylene propylene diene monomer, styrene-butadiene-styrene block copolymer (SBS) and styrene-isoprene-styrene block copolymer As a non-polar organic film layer material. Among them, the polybasic hydrocarbons include polyethylene, polypropylene, polyisobutylene and the like. When the non-polar organic film layer is a rubber film layer, such as a rubber layer such as butadiene rubber, natural rubber, polyisoprene rubber, styrene butadiene rubber, butyl rubber, ethylene propylene rubber, and ethylene propylene diene rubber, the rubber The film layer may or may not be vulcanized.

 The non-polar organic film layer material in the degradable polymer coated slow release fertilizer of the present invention may also be a mixture of a non-polar low molecular weight organic substance and a non-polar polymer, and the non-polar low molecular weight organic substance used at this time The melting point or softening point can be lower than room temperature.

The degradable polymer for degradable polymer coated slow release fertilizer of the invention may be amino resin, acid-reducing resin of polyvinyl alcohol and copolymer thereof, unsaturated oleoresin and natural polymer and derivative thereof One or more. Among them, the natural polymer and its derivative may be one or more of nitrocellulose, shellac, cellulose acetate, crosslinked starch, chitin derivative, and lignin derivative. The degradable polymer in the degradable polymer coated slow release fertilizer coating of the present invention is water-insoluble, or although the prepolymer used is water-soluble, the degradable polymer in the finally formed film layer should be The prepolymer which becomes water-insoluble, such as a urea-formaldehyde resin and a melamine-formaldehyde resin, may be water-soluble, but the urea-formaldehyde resin and the melamine-formaldehyde resin formed by curing crosslinking become water-insoluble. Among the degradable polymers, amino resins are preferred, especially urea-formaldehyde resins and melamine-formaldehyde resins (including modified urea-formaldehyde resins and modified melamine-formaldehyde resins), which are used as degradable polymer coatings. The material of the degradable polymer-coated slow-release fertilizer of the present invention has a low fat content and a low cost. Next, the unsaturated oleoresin is a resin obtained by crosslinking an unsaturated oil, and since they can be used without a solvent in the coating process, an unsaturated oleoresin can also be preferable. Unsaturated oil refers to a natural oil containing a double bond in a molecular structure, which can undergo a cross-linking reaction, such as tung oil, soybean oil, linseed oil or dehydrated castor oil. Among them, tung oil is a low-priced natural unsaturated oil, and its The tung oil resin film formed in combination has a strong barrier property against water and fertilizer, and is a preferred unsaturated oil. In addition, high acetal acetal resins (50% acetal) and nitrocellulose, which are water-insoluble polyvinyl alcohols and copolymers thereof, are also degradable coating materials which are considered. The acetal resin of polyvinyl alcohol and its copolymer may be a formal resin, a acetal resin or a butyral resin of polyvinyl alcohol and a copolymer thereof.

 In order to adjust the properties of the sulfur-containing degradable polymer mixture film layer and the degradable polymer film layer, such as toughness, a low molecular organic substance such as a sulfur-containing degradable polymer mixture film layer and a degradable polymer film layer may be added. A plasticizer or the like may be added with a small amount of a bactericide or a bacteriostatic agent (preferably a water-insoluble bactericide or a bacteriostatic agent).

 In the film of the sulfur-containing degradable polymer mixture of the degradable polymer coated slow-release fertilizer of the present invention, the average mass fraction of sulfur may be between 0% and 95%. However, when the sulfur content is too low, the effect of sulfur on the barrier property of the film is not obvious, but when the temperature is too high, the toughness of the film is low and brittle, so it is preferably between 20% and 95%. Fortunately between 50% and 90%. If necessary, a certain amount of plasticizer may be added to the film of the sulfur-containing degradable polymer mixture to increase the toughness of the film; of course, the tough polymer-enhancing film may be mixed in the film layer of the sulfur-containing degradable polymer mixture. The toughness of the layer, but since the tough polymer is mostly a poorly degradable polymer, it is not preferred. At the same time, it is also possible to form a sulfur-containing gradient distribution in the film layer of the sulfur-containing degradable polymer mixture, for example, a sulfur-containing degradable polymer mixture film which is outward in the ruthenium barrier organic film layer (ie, opposite to the direction toward the fertilizer core). In the layer, the sulfur content can be gradually reduced from the inside to the outside, and the low sulfur content of the outer layer can make the outer layer have high toughness. When the sulfur content of the sulfur-containing degradable polymer mixture film layer of the high barrier organic film layer is high, for example, 80% or more, the sulfur-containing degradable polymer mixture may have a thin layer outside the film layer (for example, 3~) 10 m) of degradable polymer film to better protect the inner film.

Since the non-polar low molecular weight organic film layer has no extensibility, the non-polar low molecular weight organic film layer is used as the high barrier organic film layer of the present invention, and the degradable polymer coated slow release fertilizer of the present invention is used in the process. The non-polar low molecular weight organic film layer is prone to cracking, so the release period is inferior to the degradable polymer coated slow release fertilizer of the present invention using the extensible non-polar polymer film layer as the high barrier organic film layer. It is long, and therefore, for the degradable polymer-coated slow-release fertilizer of the present invention which has a long release period, it is preferred that the high-barrier organic film layer is a non-polar polymer film layer. Of course, since most of the layers of the non-polar low-molecular-weight organic film layer can still be continuous layers, and the continuous film layer still exhibits a barrier effect, the non-polar low-molecular-weight organic film layer is high-resistance. The degradable polymer coated slow release fertilizer of the present invention having a permeable organic film layer can still have a long release period.

 For the degradable polymer coated slow release fertilizer of the present invention, the degradable polymer film layer and the I or sulfur degradable polymer mixture film layer provide sufficient mechanical strength and rigidity to bear the support of the fertilizer core water swelling. The expansion force ensures that the entire envelope is not broken. However, the degradable polymer generally has a high water absorption rate. Therefore, the degradable polymer-coated slow-release fertilizer of the present invention will absorb water and swell after being exposed to water in the field. In order to make the entire envelope have a barrier property imparted by the high barrier organic film layer, the high barrier organic film layer of the degradable polymer coated slow release fertilizer of the present invention is preferably not broken. Therefore, it is preferable to use a barrier polymer (including a mixture of a high barrier polymer and a low molecular weight organic substance) as a material of a high barrier organic film layer, or a layer of a high barrier organic film. A separate high barrier polymer film layer. Moreover, the high-barrier polymer film layer in the high-barrier organic film layer preferably has a higher elongation at break than the coated film of the degradable polymer-coated slow-release fertilizer, and the entire envelope occurs when immersed in water. The equilibrium expansion ratio of swelling is such that when the degradable polymer-coated slow-release fertilizer is immersed in water, cracks occur due to swelling of the entire envelope. Therefore, it is preferable to use a high-barrier polymer having a large elongation at break for the high-barrier organic film layer. Of course, a non-polar polymer having a large elongation at break, such as a non-polar elastomer, is preferably used.

 The degradable polymer coated slow release fertilizer of the invention can be adjusted by adding a slow release modifier to the high barrier organic film layer to adjust the release period of the degradable polymer coated slow release fertilizer of the invention, so that the release period can be free design. There are many types of slow release modifiers that can be added, such as plasticizers, water-soluble compounds, vegetable powders, long-chain fatty acids, and additives that increase the permeability of high-barrier organic membranes to water and fertilizers. The ester, the long-chain fatty alcohol, the rosin and its ester, the asphalt, the clay, the talc, the molecular sieve powder or the bone powder may be one type or more than one type. For example, adding a plasticizer to the non-polar polymer film layer (plasticizers are basically polar low molecular organic substances), water-soluble compounds (including fertilizer itself), starch, wood flour, plant chips, asphalt, clay The talc powder, molecular sieve powder or bone powder can improve the permeability of the high barrier organic film layer to water and fertilizer to adjust the release period of the degradable polymer coated slow release fertilizer of the present invention. For example, in a non-polar low molecular weight organic film layer, polar group-added additives such as chlorinated paraffin, rosin and esters thereof, asphalt, long-chain fatty acids and esters thereof, long-chain fatty alcohols, etc. may also be added. Water-soluble compounds (including fertilizer itself), starch, wood flour, plant chips, clay, talc, molecular sieve powder or bone meal. It is of course also possible to add other additives, even degradable polymers.

 The total average thickness of the coating of the degradable polymer coated slow-release fertilizer of the present invention may be between SO SOO/^ m, and the total average thickness of the high-barrier organic film layer may be between 2 and 25 μm. The total average thickness of both the degraded polymer film layer and the sulfur-containing degradable polymer mixture film layer may be between 20 and 190 / m; wherein the total average thickness of the degradable polymer film layer may be between 0 and 190 m The total average thickness of the film of the sulfur-containing degradable polymer mixture may be between 0 and 190 m.

Of course, the total average thickness of the envelope, the total average thickness of the high barrier organic film layer, the degradable polymer film layer and The total average thickness of both the sulfur degradable polymer mixture film layers, the total average thickness of the sulfur-containing degradable polymer mixture film layers, and the total average thickness of the degradable polymer film layers may all be higher than the respective upper limits set forth above. Bigger. The greater these thicknesses, the longer the release period of the degradable polymer coated slow release fertilizer of the present invention.

 Due to the different surface properties between the fertilizer, sulfur, degradable polymer and the high barrier organic film layer material, in order to adjust the mutual wetting and spreading film formation and/or binding between them, it is possible to A surfactant is added to the coating liquid of the sulfur-containing degradable polymer and the high-barrier organic film layer material.

 In addition, other additives may be added to the sulfur-containing degradable polymer mixture film layer, the degradable polymer film layer and the high-barrier organic film layer in the degradable polymer-coated slow-release fertilizer coating of the present invention. In order to achieve such things as further adjusting the performance of the film layer or reducing the cost and the like. For example, by adding an incremental barrier filler (preferably a nanofiller) such as calcium carbonate to the sulfur-containing degradable polymer mixture membrane layer and the I or degradable polymer membrane layer, the cost can be reduced, and at the same time It can improve the barrier property of the film.

 Hereinafter, the degradable polymer-coated slow-release urea of the present invention using urea as a fertilizer core as an example illustrates the specific implementation method and invention effect of the degradable polymer-coated slow-release fertilizer of the present invention. The sustained release property is evaluated by a dissolution method in water. The dissolution method in water is a method for determining the dissolution rate of urea in water in the degradable polymer coated slow release urea of the present invention, and the specific method is as follows: 10 g of the degradable polymer coating type of the present invention The slow-release urea was immersed in 200 ml of water and immersed at a constant temperature of 25 ° C to measure the initial dissolution rate and the average differential dissolution rate. The initial dissolution rate ^ refers to the percentage of urea dissolved in the first 24 hours of immersion in the total mass of urea in the degradable polymer coated slow release urea of the present invention, and the average differential dissolution rate is from The average amount of urea dissolved per day from the second day to the seventh day of soaking is 10% of the total mass of urea in the degradable polymer coated slow release urea of the present invention. According to the initial dissolution rate ^ and the average differential dissolution rate ^, Calculating the release period t (days) of the degradable polymer coated slow release urea in water of the present invention:

 1 - 1

 t = ~~— + 1

ψ _η ,

 Example 1

The granular industrial urea having a particle diameter of 2.0 to 4.0 mm is introduced into the fluidized bed coating device, and the granular urea is in a boiling state, and the temperature of the granular urea in the fluidized bed is maintained at 70 °C. Spraying a cyclohexane solution of styrene-butadiene-styrene block copolymer onto the surface of granular urea, spraying until the formed styrene-butadiene-styrene block copolymer film quality reaches the final product degradable 3% of the total mass of the polymer-coated slow-release urea was sufficiently dried to remove cyclohexanone from the film layer. Then, a urea-formaldehyde resin prepolymer aqueous solution is sprayed on the surface of the styrene-butadiene-styrene block copolymer film layer (the urea-formaldehyde resin prepolymer is prepared by reacting urea with formaldehyde in a molar ratio of 1:1.3). Until the formed urea-formaldehyde resin film layer reaches 17% of the total mass of the final finished degradable polymer-coated slow-release urea. Fully drying to remove water in the film layer, and curing the urea-formaldehyde resin in the film layer sufficiently, that is, degradable Polymer coated slow release urea. The release period of the degradable polymer coated slow release urea produced was 98 days. Example 2

 The granular industrial urea having a particle diameter of 2.0 to 4.0 mm is introduced into the fluidized bed coating device, and the granular urea is in a boiling state, and the temperature of the granular urea in the fluidized bed is maintained at 65 °C. Paraffin wax (melting point 75 Ό) was melt sprayed onto the urea surface until the quality of the paraffin layer formed reached 3% of the total mass of the final product degradable polymer coated slow release urea. Then, spraying the benzene solution of the butadiene rubber raw rubber on the surface of the paraffin film layer until the quality of the formed butadiene rubber raw rubber film layer reaches 1% of the total mass of the final product degradable polymer coated type slow release urea, and the vacuum drying is sufficient. The benzene in the film layer is removed. Finally, a melamine-formaldehyde resin prepolymer aqueous solution is sprayed on the surface of the butadiene rubber raw rubber film layer (melamine-formaldehyde resin prepolymer is prepared by reacting melamine with formaldehyde in a molar ratio of 1:3) until formaldehyde is formed. The melamine-formaldehyde resin film has a quality of 17% of the total mass of the final product degradable polymer coated slow release urea. The vacuum drying sufficiently removes the water in the film layer, and the melamine-formaldehyde resin in the film layer is sufficiently cured to obtain a degradable polymer-coated sustained-release urea. The release period of the degradable polymer coated slow release urea produced was 115 days.

 Example 3

 The granular industrial urea with a particle size of 2.0 to 4.0 mm is added to the fluidized bed coating equipment, and the granular urea is in a boiling state, and the granular urea temperature in the fluidized bed is maintained at 80 C. Tung oil (a drier containing 0.4% tung oil) was sprayed onto the urea surface until the quality of the tung oil resin film layer reached 18% of the total mass of the final product degradable polymer coated slow release urea. Then, a polyethylene wax (molecular weight 1800) benzene solution was sprayed on the surface of the tung oil resin film layer until the quality of the formed polyethylene wax film layer reached 4% of the total mass of the final product degradable polymer coated type slow release urea. The benzene in the film layer is sufficiently dried and the tung oil resin in the film layer is sufficiently cured to obtain a degradable polymer-coated sustained-release urea. The release period of the degradable polymer coated slow release urea produced was 125 days.

 Example 4

The granular industrial urea with a particle size of 2.0-4.0 mm is added to the fluidized bed coating device, and the granular urea is in a boiling state, and the granular urea temperature in the fluidized bed is maintained at 65 °C. Tung oil (a drier containing 0.4% of tung oil) was sprayed on the urea surface until the quality of the tung oil resin film layer reached 6% of the total mass of the final product degradable polymer coated slow release urea. Then, a paraffin wax having a melting point of 75 石 is sprayed on the surface of the tung oil resin film layer until the quality of the formed paraffin film layer reaches 4% of the total mass of the final product degradable polymer film type slow release urea. Finally, the surface of the paraffin layer is sprayed with tung oil (containing 0.4% of the tung oil quality of the tanning agent) until the quality of the tung oil resin film layer reaches 14% of the total mass of the final product degradable polymer coated slow release urea. . The tung oil resin in the film layer is sufficiently cured to obtain a degradable polymer-coated sustained-release urea. The release period of the degradable polymer coated slow release urea produced was ₁₄ 2 days.

Example 5 The granular industrial urea having a particle diameter of 2.0 to 4.0 mm is introduced into the fluidized bed coating device, and the granular urea is in a boiling state, and the temperature of the granular urea in the fluidized bed is maintained at 70 °C. Spraying a nitrocellulose solution (a solvent mixture of ethanol, acetone and amyl acetate) on the surface of granular urea, spraying until the quality of the formed nitrocellulose membrane reaches the final product of degradable polymer coated slow release urea 10% of the total mass, the solvent in the film layer is removed by drying. Then, a benzene solution of a petroleum resin (softening point of 110 ° C) was sprayed on the surface of the nitrocellulose membrane layer until the quality of the petroleum resin film layer formed reached 2% of the total mass of the final product degradable polymer coated slow release urea. Then, the benzene solution of the butadiene rubber raw rubber is sprayed on the surface of the petroleum resin film layer until the quality of the formed butadiene rubber raw rubber film layer reaches 1% of the total mass of the final product degradable polymer coated type slow release urea. Finally, the nitrocellulose solution is sprayed on the surface of the butadiene rubber raw rubber film layer until the quality of the formed nitrocellulose film layer reaches 8% of the total mass of the final product degradable polymer coated slow release urea. The solvent in the film layer is sufficiently dried to obtain a degradable polymer-coated sustained-release urea. The release period of the degradable polymer coated slow release urea produced was 102 days.

 Example 6

 The granular industrial urea with a particle size of 2.0~4.0mm is added to the fluidized bed coating equipment, and the granular urea is in a boiling state, and the granular urea temperature in the fluidized bed is maintained at 95 Ό. Spraying a toluene solution of polyethylene and paraffin mixture (polyethylene: paraffin mass ratio of 4:1) on the surface of granular urea until the formed polyethylene-paraffin mixture film quality reaches the final product degradable polymer coating type sustained release 3% of the total mass of urea, fully dried to remove toluene from the film. Then, spraying a sulphur-containing melamine-formaldehyde resin prepolymer aqueous solution on the surface of the polyethylene-paraffin mixture film layer (melamine-formaldehyde resin prepolymer is prepared by reacting melamine: melamine having a molar ratio of 1:3 with formaldehyde, Sulfur: The mass ratio of the melamine-formaldehyde resin prepolymer is 7:3) until the film quality of the formed sulfur-containing melamine-formaldehyde resin mixture reaches 18% of the total mass of the final product degradable polymer-coated slow release urea. The water is sufficiently dried to remove the water in the film layer, and the melamine-formaldehyde resin in the film layer is sufficiently cured to obtain a degradable polymer-coated sustained-release urea. The release period of the degradable polymer-coated slow release urea produced was 126 days.

 Example 7

The granular industrial urea with a particle size of 2.0-4.0 mm is added to the fluidized bed coating device, and the granular urea is in a boiling state, and the granular urea temperature in the fluidized bed is maintained at 75 °C. The benzene solution of ethylene propylene rubber mixture (100 parts of ethylene propylene rubber raw rubber and 1.5 parts of benzoyl peroxide) is sprayed on the surface of urea until the quality of the formed ethylene propylene rubber compound film reaches the final product. The 3% of the total mass of the degradable polymer coated slow release urea is sufficiently dried to remove benzene from the film. Then, the tung oil and about 150 熔融 of molten sulfur are sprayed from the two different nozzles to the surface of the ethylene-propylene rubber compound film layer, and the formed sulfur-containing tung oil resin mixture film layer is formed by controlling the spray flow ratio thereof. The average mass fraction of sulfur in the medium is 80%, and the film quality until the formation of the sulfur-containing tung oil resin mixture reaches 15% of the total mass of the final product degradable polymer-coated sustained-release urea. Finally, stop Spray molten sulfur and continue to spray tung oil (containing a drier of 0.4% tung oil) until the quality of the tung oil resin film reaches 4% of the total mass of the final product degradable polymer coated slow release urea. The ethylene-propylene rubber compound in the film layer is vulcanized sufficiently and the tung oil resin is sufficiently cured to obtain a degradable polymer coated type slow-release urea. The release period of the degradable polymer coated slow release urea produced was 158 days.

 Example 8

 The granular industrial urea having a particle diameter of 2.0 to 4.0 mm is introduced into the fluidized bed coating device, and the granular urea is in a boiling state, and the temperature of the granular urea in the fluidized bed is maintained at 70 °C. The tung oil and molten sulfur at about 150 °C were sprayed from the two different nozzles to the urea surface at the same time. By controlling their spray flow ratio, the average mass fraction of sulfur in the formed sulfur-containing tung oil resin mixture film layer was 80%, sprayed until the film quality of the formed sulfur-containing tung oil resin mixture reaches 16% of the total mass of the final product degradable polymer coated slow release urea. Then, a surface of the film of the sulfur-containing tung oil resin mixture is sprayed with a petroleum resin (100 软化 softening point) benzene solution until the quality of the petroleum resin film layer formed reaches 2% of the total mass of the final product degradable polymer-coated slow release urea. Finally, a solvent-based gasoline solution of styrene-butadiene rubber raw rubber is sprayed on the surface of the petroleum resin film layer until the formed styrene-butadiene rubber raw rubber film layer reaches 1% of the total mass of the final product degradable polymer-coated slow-release urea. The benzene and solvent gasoline in the film layer are sufficiently dried and the tung oil resin is sufficiently cured to obtain a degradable polymer-coated sustained-release urea. The release period of the degradable polymer coated slow release urea produced was 136 days.

 Example 9

 The granular industrial urea with a particle size of 2.0 to 4.0 mm was placed in a drum-controlled equipment with a temperature control of 80 Torr, and the rotating drum (rotation speed of 40 r/min) was used to flow the granular urea in the drum. A polyethylene wax (molecular weight 1500) benzene solution was sprayed onto the urea surface until the polyethylene film layer formed reached 3% of the total mass of the final product degradable polymer coated urea. Then, spraying the benzene solution of the butadiene rubber raw rubber on the surface of the polyethylene wax film layer until the quality of the formed butadiene rubber raw rubber film layer reaches 1% of the total mass of the final product degradable polymer coated type slow release urea. Drying removes benzene from the film layer. Finally, the surface of the butadiene rubber film layer is sprayed with sulfur-containing tung oil (containing 0.4% drier of tung oil, sulfur: tung oil mass ratio is 1:1) until the formed sulfur-containing tung oil resin mixture film layer The quality reaches 20% of the total mass of the final product degradable polymer coated slow release urea. The tung oil resin in the film layer is sufficiently cured to obtain a degradable polymer coated type slow release urea. The release period of the degradable polymer coated slow release urea produced was 151 days.

 Example 10

The granular industrial urea with a particle size of 2.0~4.0mm is added to the fluidized bed coating equipment, and the granular urea is in a boiling state, and the granular urea temperature in the fluidized bed is maintained at 80Ό. A benzene solution of a petroleum resin (softening point of 110 ° C) was sprayed on the surface of the granular urea film layer until the quality of the formed petroleum resin film layer reached 3% of the total mass of the final product degradable polymer coated type slow release urea. Then, the nitrocellulose solution (solvent is ethanol, acetone and acetic acid The mixed solvent of the esters and the molten sulfur of about 150 ° C are sprayed from the two different nozzles simultaneously to the surface of the petroleum resin film layer, and the sulfur-containing nitrocellulose mixture is formed by controlling the spray flow ratio thereof. The average mass fraction of sulfur in the film was 75%, and the film quality of the sulfur-containing nitrocellulose mixture formed until the formation reached 17% of the total mass of the final product degradable polymer coated slow release urea. Finally, the spraying of molten sulfur is stopped, and the nitrocellulose solution is continuously sprayed until the quality of the formed nitrocellulose membrane reaches 2% of the total mass of the final product degradable polymer coated slow release urea. The solvent in the film layer is sufficiently dried to obtain a degradable polymer-coated sustained-release urea. The release period of the degradable polymer coated slow release urea produced was 113 days.

 Example 11

 The granular industrial urea with a particle size of 2.0~4.0mm is added to the fluidized bed coating equipment, and the granular urea is in a boiling state, and the granular urea temperature in the fluidized bed is maintained at 80Ό. A sulphur-containing melamine-formaldehyde resin prepolymer aqueous solution (melamine-formaldehyde resin prepolymer is prepared by reacting melamine:melamine molar ratio of 1:3 with melamine and sulfur: melamine-formaldehyde resin prepolymer) 4: 1 ) spraying on the urea surface until the formed layer of the sulfur-containing melamine-formaldehyde resin mixture reaches 8% of the total mass of the final product degradable polymer coated slow release urea, and is sufficiently dried to remove the film layer. water. Then, spraying a high impact polystyrene benzene solution on the surface of the sulfur-containing melamine-formaldehyde resin mixture film layer until the quality of the high impact polystyrene film layer formed reaches the final quality of the final product degradable polymer coated type slow release urea 3%, fully dried to remove benzene from the film. Then, a melamine-formaldehyde resin prepolymer aqueous solution (melamine-formaldehyde resin prepolymer is prepared by reacting melamine:melamine with a molar ratio of 1:3 and formaldehyde) and 15 (about TC of molten sulfur) from two groups respectively. Different nozzles are simultaneously sprayed onto the surface of the high-impact polystyrene film layer. By controlling their spray flow ratio, the average mass fraction of sulfur in the formed sulfur-containing melamine-formaldehyde resin mixture layer is 80%, and spraying until The formed layer of the sulfur-containing melamine-formic acid resin mixture has a film quality of 8% of the total mass of the final product degradable polymer-coated slow-release urea. Finally, the spraying of the molten sulfur is stopped, and the melamine-formaldehyde resin pre-polymerization is continuously sprayed. Aqueous solution (melamine-formaldehyde resin prepolymer is prepared by reacting melamine with a formaldehyde molar ratio of 1:1.6 in melamine and formaldehyde) until the quality of the layer of melamine-formaldehyde resin formed reaches the final product degradable polymer coating 2% of the total mass of sustained-release urea. Water, and a melamine formaldehyde resin layer is sufficiently cured, to give the slow release biodegradable polymer coated urea. The resulting coated release type of sustained release biodegradable polymer is a urea 146 days.

 Example 12

The granular industrial urea having a particle diameter of 2.0 to 4.0 mm is introduced into the fluidized bed coating device, and the granular urea is in a boiling state, and the temperature of the granular urea in the fluidized bed is maintained at 80 °C. Tung oil (a drier containing 0.4% of tung oil) and molten sulfur of about 150 °C were sprayed from the two different nozzles simultaneously to the urea surface, and the sulfur-containing tung oil was formed by controlling their spray flow ratio. The average mass fraction of sulfur in the resin mixture film layer is 70%, sprayed until the formed layer of the sulfur-containing tung oil resin mixture has a film quality of 10% of the total mass of the final product degradable polymer coated slow release urea. Then, spraying a polyethylene wax on the surface of the sulfur-containing tung oil resin mixture film layer

(Molecular weight 1000) benzene solution until the quality of the formed polyethylene wax film layer reaches 2% of the total mass of the final product degradable polymer coated slow release urea, and the benzene in the film layer is sufficiently dried. Subsequently, a mixture of 4, 4-diphenylformamidine diisocyanate MDI, triethanolamine and polypropylene glycol, =2000 was sprayed on the surface of the polyethylene wax film layer.

(triethanolamine: polypropylene glycol molar ratio is 0.1: 1, -NCO: -OH molar ratio is 1.1: 1), until the quality of the formed polyurethane resin film reaches the final product of degradable polymer coated slow release urea 1% of the mass. Finally, the surface of the polyurethane resin film is sprayed with sulfur-containing tung oil (containing 0.4% drier of tung oil, and the ratio of sulfur: tung oil is 1:1) until the quality of the layer of the sulfur-containing tung oil resin mixture is formed. 8% of the total mass of the final product degradable polymer coated slow release urea. The polyurethane resin and the tung oil resin in the film layer are sufficiently cured to obtain a degradable polymer-coated sustained-release urea. The release period of the degradable polymer-coated sustained-release urea produced was 140 days.

 Example 13

 The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and each film layer coating method is the method described in the foregoing embodiment or other suitable method. The first film layer on the surface of the granular urea is a sulfur-containing polyvinyl formal resin mixture film layer having a sulfur content of 80% (a polyvinyl alcohol-formaldehyde resin having a polyvinyl alcohol type 1799 and an acetal degree of 90%). - The solution of the toluene mixed solvent is sprayed and formed into a film, wherein the solution contains sulfur, and the sulfur: polyvinyl formal resin mass ratio is 2:3), and the film layer occupies the final product of the degradable polymer coating type. Released 16% of the total mass of urea. The second film layer is an ethylene-propylene rubber vulcanized rubber film layer (formed by vulcanization of a solution of 100 parts of ethylene propylene rubber and 1.5 parts of a vulcanizing agent DCP), and the film layer occupies the final product degradable polymer package. 3% of the total mass of membrane type slow release urea. The third film layer is a polyvinyl butyral resin film layer (obtained by spraying and forming a film of a polyvinyl butyral resin having a polyvinyl alcohol type 1799 and a acetal degree of 60%), and the film layer is formed. It accounts for 2% of the total mass of the final product degradable polymer coated slow release urea. The release period of the degradable polymer-coated slow release urea produced was 113 days.

 Example 14

The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and each film layer coating method adopts the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the granular urea is a melamine-formaldehyde resin film layer (the melamine-formaldehyde resin prepolymer prepared by reacting melamine and formaldehyde with a molar ratio of 1:4 and formaldehyde is sprayed into a film and cured. The film layer accounts for 3% of the total mass of the final product degradable polymer coated slow release urea. The second film layer is a film layer of polyethylene and butadiene rubber raw rubber mixture (formed by spraying a toluene solution of polyethylene and butadiene rubber), and the mass ratio of polyethylene to butadiene rubber is 4 : 1), the film layer accounts for 3% of the total mass of the final product degradable polymer coated slow release urea. Third The film layer is a sulfur-containing melamine-formaldehyde resin mixture film layer with a sulfur content of 70% (the melamine-formaldehyde resin prepolymer aqueous solution is simultaneously sprayed with molten sulfur to form a film, and the melamine-formaldehyde resin prepolymer is melamine. : The molar ratio of formaldehyde to 1:3 is prepared by reacting melamine with formaldehyde), which constitutes 17% of the total mass of the final product degradable polymer coated slow release urea. The release period of the degradable polymer coated slow release urea produced was 135 days.

 Example 15

 The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and the coating method of each film layer is carried out by the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the granular urea is a tung oil resin film layer, which accounts for 6% of the total mass of the final product degradable polymer coated type slow release urea. The second film layer is a mixture of paraffin and rosin (a mixture of paraffin and rosin is melt-sprayed to form a film, the mass ratio of paraffin to rosin is 3:1, the melting point of the mixture is 80 ° C), the film layer It accounts for 4% of the total mass of the final finished degradable polymer coated slow release urea. The third film layer is a tung oil resin film layer which accounts for 14% of the total mass of the final product degradable polymer film type slow release urea. The release period of the degradable polymer coated slow release urea produced was 98 days.

 Example 16

 The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and each film layer coating method employs the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the granular urea is a sulfur-containing melamine-formaldehyde resin mixture film layer having a sulfur content of 80% (the melamine-formaldehyde resin prepolymer aqueous solution is melted and melted at the same time as the molten sulfur to form a film, and the melamine is obtained. The one formaldehyde resin prepolymer is prepared by reacting melamine with a molar ratio of 1:3 in melamine and formaldehyde, and the film layer accounts for 8% of the total mass of the final product degradable polymer coated slow release urea. The second film layer is a triphenyl phosphate plasticized polystyrene film layer (formed by spraying a film of polystyrene toluene containing triphenyl phosphate), and the triphenyl phosphate: polystyrene mass ratio is 3: 2) The film layer accounts for 3% of the total mass of the final product degradable polymer coated slow release urea. The third film layer is a sulfur-containing melamine-formaldehyde resin mixture film layer having a sulfur content of 80% (a melamine-formaldehyde resin prepolymer aqueous solution and a molten sulfur are simultaneously sprayed and formed into a film, and then cured, the melamine-formaldehyde resin prepolymer is obtained. It is melamine: a molar ratio of 1:3 melamine to formaldehyde, which is 8% of the total mass of the final product degradable polymer coated slow release urea. The fourth film layer is a melamine-formaldehyde resin film layer (melamine: a melamine-formaldehyde resin prepolymer prepared by reacting melamine with formaldehyde in a molar ratio of 1:2 and formaldehyde) is sprayed and formed into a film, and the film layer is formed. It accounts for 2% of the total mass of the final product degradable polymer coated slow release urea. The release period of the degradable polymer coated slow release urea produced was 81 days.

 Example 17

The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and each film layer coating method is the method described in the foregoing embodiment or other suitable method. The first film layer on the surface of granular urea is melamine-formaldehyde Resin film layer (using a melamine-formaldehyde molar ratio of 1:3.5 melamine and formaldehyde to prepare a solution of melamine-formaldehyde resin prepolymer prepared by spraying and curing the film), the film layer occupies the final product degradable polymer package 3% of the total mass of membrane type slow release urea. The second film layer is a sulfur-containing melamine-formaldehyde resin mixture film layer having a sulfur content of 80% (a melamine-formaldehyde resin prepolymer aqueous solution and a molten sulfur are simultaneously sprayed and formed into a film, and then cured, the melamine-formaldehyde resin prepolymer is obtained. It is prepared by reacting melamine with a formaldehyde molar ratio of 1:3 and melamine, and the film layer accounts for 16% of the total mass of the final product degradable polymer coated slow release urea. The third film layer is a styrene-butadiene-styrene block copolymer film layer (a film formed by spraying a cyclohexyl styrene solution of a styrene-butadiene-styrene block copolymer), the film layer It accounts for 2% of the total mass of the final product degradable polymer coated slow release urea. The release period of the degradable polymer coated slow release urea produced was 110 days.

 Example 18

 The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and the coating method of each film layer is carried out by the method described in the foregoing examples or other suitable methods. The first film layer on the surface of granular urea is sepiolite (particle size 25 m) with a mass fraction of 6% containing a layer of sepiolite styrene-butadiene-styrene block copolymer mixture. A film of styrene-butadiene-styrene block copolymer of sepiolite is sprayed into a film, and the film layer accounts for 3% of the total mass of the degradable polymer-coated sustained-release urea. The second film layer is a urea-formaldehyde resin film layer (a urea-formaldehyde resin prepolymer prepared by reacting urea and formaldehyde with a formaldehyde molar ratio of 1:1.3 is sprayed and formed into a film and solidified), and the film layer is degradable polymerization. 17% of the total mass of the coated slow release urea. The release period of the degradable polymer coated slow release urea produced was 56 days.

 Example 19

 The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and each film layer coating method is the method described in the foregoing examples or other suitable methods. The first layer of granular urea surface is a montmorillonite (particle size 25 m) mass fraction of 15% montmorillonite styrene-butadiene-styrene block copolymer mixture film layer The film of the demineralized styrene-butadiene-styrene block copolymer was sprayed into a film, and the film layer accounted for 3% of the total mass of the degradable polymer-coated sustained-release urea. The second film layer is a urea-formaldehyde resin film layer (the urea-formaldehyde resin prepolymer prepared by reacting urea with formaldehyde in a molar ratio of 1:1.3 is sprayed and formed into a film and solidified), and the film layer is degradable. 17% of the total mass of the polymer coated slow release urea. The release period of the degradable polymer coated slow release urea produced was 28 days.

 Example 20

The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and each film layer coating method adopts the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the granular urea is a butadiene rubber vulcanized rubber film layer (cured by spraying a film of toluene solution prepared by using 100 parts of butadiene rubber and 1.5 parts of a vulcanizing agent DCP), and the film layer is occupied. Degradation of polymer coated type slow release urea by 1% of total mass. The second film is the sulfur mass fraction. It is a 50% sulfur-containing tung oil resin mixture film layer (cured by simultaneous casting of tung oil and molten sulfur into a film), and the film layer accounts for 22% of the total mass of the degradable polymer coated type slow-release urea. The release period of the degradable polymer coated slow release urea produced was 78 days.

 Example 21

 The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and the coating method of each film layer is carried out by the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the granular urea is a melamine-formaldehyde resin film layer (after the filming of the melamine-formaldehyde resin prepolymer prepared by reacting melamine and formaldehyde with a molar ratio of 1:3.5 in formaldehyde, the film is sprayed into a film. The film layer accounts for 2% of the total mass of the degradable polymer coated slow release urea. The second film layer is a styrene-butadiene-styrene block copolymer film layer which accounts for 1% of the total mass of the degradable polymer-coated sustained-release urea. The third film layer is a nitrocellulose film layer which accounts for 10% of the total mass of the degradable polymer coated slow release urea. The release period of the degradable polymer-coated sustained-release urea produced was 35 days.

 Example 22

 The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and the coating method of each film layer is carried out by the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the granular urea is a melamine-formaldehyde resin film layer (the melamine-formaldehyde resin prepolymer prepared by reacting melamine and formaldehyde with a molar ratio of 1:3.5 and formaldehyde is sprayed into a film and cured. The film layer accounts for 2% of the total mass of the degradable polymer coated slow release urea. The second film layer is a styrene-butadiene-styrene block copolymer film layer which accounts for 1% of the total mass of the degradable polymer-coated sustained-release urea. The third film layer is a nitrile rubber raw rubber film layer obtained by spraying a film of a nitrile rubber in a toluene solution, and the film layer accounts for 1.5% of the total mass of the degradable polymer coated type sustained-release urea. The fourth film layer is a nitrocellulose film layer, which accounts for 8.5% of the total mass of the degradable polymer coated slow release urea. The release period of the degradable polymer coated slow release urea produced was 65 days.

 Example 23

The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and each film layer coating method adopts the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the granular urea is a sulfur-containing melamine-formaldehyde resin mixture film layer with a sulfur content of 80% (the melamine-formaldehyde resin prepolymer aqueous solution and the molten sulfur are simultaneously sprayed and formed into a film, and the melamine is obtained. The formaldehyde resin prepolymer is prepared by reacting melamine with a formaldehyde molar ratio of 1:2.8 and melamine, and the film layer accounts for 6% of the total mass of the degradable polymer coated slow release urea. The second film layer is a ruthenium impact polystyrene film layer (which is obtained by spraying a film of a toluene solution of high impact polystyrene), and the film layer accounts for 1 of the total mass of the degradable polymer film type slow release urea. %. The third film layer is a tung oil resin film layer, which accounts for 3% of the total mass of the degradable polymer film type slow release urea. The release period of the degradable polymer coated slow release urea produced was 59 days. Example 24

 The raw material urea used is flaky urea of Φ8χ3ιηπι, and the coating method of each film layer adopts the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the flaky urea is a tung oil resin film layer, which accounts for 6% of the total mass of the degradable polymer-coated sustained-release urea. The second film layer is a petroleum resin (softening point of 100 ° C) film layer, which accounts for 2% of the total mass of the degradable polymer film type slow release urea. The third film layer is a tung oil resin film layer which accounts for 10% of the total mass of the degradable polymer film type slow release urea. The release period of the degradable polymer-coated sustained-release urea obtained was 245 days.

 Example 25

 The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and the coating method of each film layer is carried out by the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the granular urea is a film layer of sulfur-containing tung oil resin mixture having a sulfur content of 80%, and the film layer accounts for 10% of the total mass of the degradable polymer-coated sustained-release urea. The second film layer is a bituminous film layer (obtained by melt-spraying a film of No. 30 bitumen), which accounts for 3% of the total mass of the degradable polymer-coated slow-release urea. The third film layer is a sulfur-containing tung oil resin mixture film layer having a sulfur content of 50%, which accounts for 8% of the total mass of the degradable polymer-coated slow-release urea. The release period of the degradable polymer-coated slow release urea produced was 76 days.

 Example 26

 The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and the coating method of each film layer is carried out by the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the granular urea is a urea-formaldehyde resin film layer (which is obtained by spraying and forming a urea-waking resin prepolymer aqueous solution prepared by reacting urea with formaldehyde in a molar ratio of 1:1.8) to form a film. The film layer accounts for 2% of the total mass of the degradable polymer coated slow release urea. The second film layer is an acrylonitrile-butadiene-styrene copolymer film layer obtained by spraying a film of acrylonitrile-butadiene-styrene copolymer ABS in a dichloroethane solution, and the film layer can be occupied. Degraded 3% of the total mass of the polymer coated slow release urea. The third film layer is a sulfur-containing urea-formaldehyde resin mixture film layer having a sulfur content of 80% (cured by a urea-formaldehyde resin prepolymer aqueous solution and molten sulfur simultaneously sprayed to form a film, and the urea-formaldehyde resin prepolymer is obtained from urea: formaldehyde molar The ratio of 1:6 urea to formaldehyde is prepared), and the film layer accounts for 10% of the total mass of the degradable polymer coated slow release urea. The fourth film layer is a urea-formaldehyde resin film layer (which is obtained by spraying and forming a urea-formaldehyde resin prepolymer aqueous solution prepared by reacting urea and formaldehyde with a molar ratio of 1:1.05 and formaldehyde), and the film layer is degradable polymerization. 2% of the total mass of the coated slow release urea. The release period of the degradable polymer coated slow release urea produced was 87 days.

 Example 27

The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 min, and each film layer coating method adopts the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the granular urea is S-628 type flexible. A saturated polyester resin film layer obtained by melt-spraying and forming a film of S-628 type flexible unsaturated polyester prepolymer containing 2% BPO initiator, which is a degradable polymer coating type 7% of the total mass of slow release urea. The second film layer is a urea-formaldehyde resin film layer (cured by a urea-formaldehyde resin prepolymer prepared by reacting urea and formaldehyde with a molar ratio of 1: 1.45 and formaldehyde), and the film layer is degradable polymerized. 13% of the total mass of the coated slow release urea. The release period of the degradable polymer coated slow release urea produced was 21 days.

 Example 28

 The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4.0 mm, and the coating method of each film layer is carried out by the method described in the foregoing examples or other suitable methods. The first film layer on the surface of the granular urea is a urea-formaldehyde resin film layer

(Using urea: formaldehyde urea molar ratio of 1: 2 urea and formaldehyde prepared by the reaction of urea-formaldehyde resin prepolymer aqueous solution sprayed into a film after curing), the film layer of the degradable polymer coating type sustained-release urea total mass 1.5%. The second film layer is a sulfur-containing polyvinyl alcohol-modified urea-formaldehyde resin film layer having a sulfur content of 75% (obtained by simultaneously spraying a film of a polyvinyl alcohol-modified urea-formaldehyde resin prepolymer with molten sulfur to form a film), The film layer accounts for 8% of the total mass of the degradable polymer coated slow release urea. The third film layer is a butadiene rubber raw rubber film layer obtained by spraying a film of a butadiene rubber raw benzene solution, and the film layer accounts for 2% of the total mass of the degradable polymer coated type slow release urea. The fourth film layer is a sulfur-containing melamine modified urea-formaldehyde resin film layer having a sulfur content of 75% (obtained by using a melamine-modified urea-formaldehyde resin prepolymer aqueous solution and molten sulfur simultaneously sprayed to form a film and solidified), and the film layer can be occupied. Degraded 8% of the total mass of the polymer coated slow release urea. The fifth film layer is an ethanol-polyvinyl alcohol modified melamine-formaldehyde resin film layer

(The epoxy layer is obtained by spraying a film of a polyvinyl alcohol-modified melamine-formaldehyde resin solution into a film and curing it, and the film layer accounts for 1.5% of the total mass of the degradable polymer-coated sustained-release urea. The release period of the degradable polymer-coated slow release urea produced was 136 days.

 Example 29

The raw material urea used is granular industrial urea having a particle diameter of 2.0 to 4. (tom), and the coating method of each film layer adopts the method described in the foregoing embodiment or other suitable method. The first film layer on the surface of the granular urea is melamine one. Formaldehyde resin film layer (obtained by spraying and forming a film of melamine-formaldehyde resin prepolymer prepared by reacting melamine and formaldehyde with a molar ratio of 1:2.5 and formaldehyde), the film layer occupies a degradable polymer package 1.5% of the total mass of the membrane-type slow-release urea. The second membrane is a sulfur-containing n-butanol-modified urea-formaldehyde resin film with a sulfur content of 80% (using n-butanol-modified urea-formaldehyde resin prepolymer aqueous solution and molten sulfur) At the same time, after spraying and film-forming, the film layer accounts for 8% of the total mass of the degradable polymer-coated slow-release urea. The third film layer is a high-impact polystyrene film layer (high-impact polyphenylene) The ethylene benzene solution is sprayed into a film, and the film layer accounts for 2% of the total mass of the degradable polymer coated slow release urea. The fourth film layer is an ethanol modified melamine-formaldehyde resin film layer (using ethanol modified melamine) Monocarboxylic acid The lipid solution is sprayed into a film and solidified, and the film layer accounts for 8% of the total mass of the degradable polymer coated slow release urea. The release period of the degradable polymer coated slow release urea is 130. day. In the above examples, the polyethylene is the Q200 type of Shanghai Petrochemical Company, the 髙 impact polystyrene is FRH-1 type of Beijing Yanshan Petrochemical Company, and the polystyrene is B-1 type of Lanzhou Petrochemical Company, styrene-butadiene-benzene. The ethylene block copolymer (SBS) grade is Kraton D1101, the styrene-butadiene rubber grade is 1500, the ethylene propylene rubber is Dutral Co 034 of Italy Eni Chem, the nitrile rubber grade is NBR2007, and the butadiene rubber grade is BR9175. Tung oil is a commercially available tung oil from Qiubei, Yunnan, with an acid value of 5.0 mgKOH/g.

 In the above embodiment, the urea-formaldehyde resin prepolymer aqueous solution is prepared by reacting urea with formaldehyde, and the molar ratio of urea to formaldehyde may be 1: (1~3), which is generally known by those skilled in the art, usually 1 : ( 1-2) It is advisable to add a 2% ammonium chloride curing agent of urea-formaldehyde resin prepolymer before coating. The melamine modified urea-formaldehyde resin prepolymer aqueous solution is prepared by reacting urea, melamine and formaldehyde. The urea:melamine:formaldehyde molar ratio is 1: 1:4, and the melamine modified urea-formaldehyde resin prepolymer is added with 2% chlorine before the film coating. Ammonium curing agent. The polyvinyl alcohol modified urea-formaldehyde resin prepolymer aqueous solution is prepared by the reaction of urea, polyvinyl alcohol and formaldehyde. The urea: formaldehyde: polyvinyl alcohol (1799) mass ratio is 100: 89: 3, and the polyvinyl alcohol is added before the film coating. The urea-formaldehyde resin prepolymer has a 2% ammonium chloride curing agent. The n-butanol modified urethane resin prepolymer aqueous solution is prepared by the reaction of urea, formaldehyde and n-butanol. The urea:formaldehyde: n-butanol molar ratio is 1: 1.37: 1, and the n-butanol modified urea aldehyde is added before the film coating. Resin prepolymer mass 2% ammonium chloride curing agent.

 In the above embodiment, the aqueous solution of the melamine-formaldehyde resin prepolymer is prepared by reacting melamine with formaldehyde, and the molar ratio of melamine to formaldehyde may be in the range of 1: (1~4), which is generally known by those skilled in the art, usually It is preferred to use 1: (1.5~3.5), and add 2% ammonium chloride or triethanolammonium curing agent of melamine-formaldehyde resin prepolymer before coating. The ethanol-modified melamine-formaldehyde resin prepolymer aqueous solution is prepared by the reaction of melamine, formaldehyde and ethanol. The melamine:formaldehyde:ethanol molar ratio is 1:2.5:2, and the quality of the melamine-formaldehyde resin prepolymer added before the coating is added. 2% ammonium chloride curing agent. The ethanol-polyvinyl alcohol modified melamine-formaldehyde resin prepolymer aqueous solution is prepared by the reaction of melamine, formaldehyde, ethanol and polyvinyl alcohol, and the melamine:formaldehyde:ethanol:polyvinyl alcohol (1788) mass ratio is 100:67:12: 2.5, before the film coating, add ethanol-polyvinyl alcohol modified melamine-formaldehyde resin prepolymer mass 2% ammonium chloride curing agent.

 The modified urea-formaldehyde resin and the modified melamine-formaldehyde resin are respectively a urea-formaldehyde resin and a melamine-formaldehyde resin, and the modified urea-formaldehyde resin and modified melamine used in the above embodiments are known to those skilled in the art. The one formaldehyde resin is only the individual representative of the modified urea-formaldehyde resin and the modified melamine-formaldehyde resin, and the preparation formula of the modified urea-formaldehyde resin and the modified melamine-formaldehyde resin used can only adopt the formula of the formula, and The scope of the invention is limited. The melamine resin in the amino resin may be prepared by using glyoxal and furfural instead of formaldehyde in addition to the above (modified) melamine-formaldehyde resin, and the related embodiments are not listed in the detailed description of the present specification, but such a class Melamine resins are still within the scope of the invention.

Claims

Claim  A degradable polymer coated slow release fertilizer consisting of a fertilizer core [1] and a coating film on the outer side of the fertilizer core, characterized in that: the envelope comprises (a) a barrier organic film layer [2] (b) a layer of sulfur-containing degradable polymer mixture [3] and/or a degradable polymer film layer [4].  The degradable polymer coated slow release fertilizer according to claim 1, wherein the high barrier organic film layer is an inner layer or an intermediate layer of the entire envelope.  The degradable polymer coated slow release fertilizer according to claim 1, wherein the high barrier organic film layer is a non-polar organic film layer, and the non-polar organic film layer material is non-polar. Low molecular weight organics and I or non-polar polymers.  The degradable polymer coated slow release fertilizer according to claim 3, wherein the non-polar low molecular weight organic substance is a wax having a melting point of ≥ 40 ° C, a melting point or a softening point of ≥ 40 ° C and a molecular weight ≤ One or more of polyolefin or polystyrene of 2000 and petroleum resin having a softening point of ≥ 40 °C.  The degradable polymer coated slow release fertilizer according to claim 3, wherein the non-polar polymer is polyolefin, polystyrene, butadiene rubber, natural rubber, polyisoprene rubber , styrene-butadiene rubber, butyl rubber, ethylene propylene rubber and ethylene propylene diene monomer, styrene-butadiene-styrene block copolymer and styrene-isoprene-styrene block copolymer Kind or more.  The degradable polymer coated slow release fertilizer according to claim 1, wherein the degradable polymer is an acetal resin of an amino resin, a polyvinyl alcohol and a copolymer thereof, an unsaturated oleoresin, and a natural One or more of a polymer and a derivative thereof; wherein the natural polymer and its derivative are nitrocellulose, shellac, cellulose acetate, crosslinked starch, chitin derivative and lignin derivative One or more of them.  The degradable polymer-coated slow-release fertilizer according to claim 1, wherein the sulfur-containing degradable polymer mixture film layer has an average mass fraction of sulfur of 0% to 95%.  The degradable polymer coated slow release fertilizer according to any one of claims 1 to 7, wherein the high barrier organic film layer is a high barrier polymer film layer or high barrier property. When a high barrier polymer film layer is present in the organic film layer, the elongation at break of the high barrier polymer film layer is greater than that of the coated degradable polymer film type slow release fertilizer when immersed in water. The equilibrium expansion ratio of the swelling of the envelope.  The degradable polymer coated slow release fertilizer according to any one of claims 1 to 7, wherein the high barrier organic film layer contains a sustained release modifier.  The degradable polymer coated slow release fertilizer according to any one of claims 1 to 7, characterized in that: the total average thickness of the coating is 20 to 200 m, wherein the high barrier organic film layer The total average thickness is 2~25 m, and the total average thickness of both the degradable polymer film layer and the sulfur-containing degradable polymer mixture film layer is 20-190 m; the total average thickness of the degradable polymer film layer is 0~ The total average thickness of the 190 m, sulfur-containing degradable polymer mixture film is 0 to 190 μm.